WEDNESDAY, April 9, 2014 (HealthDay News) -- A long-term study suggests that older people who use common prescription painkillers, including prescription-strength ibuprofen, may be increasing their risk for developing a type of irregular heartbeat called atrial fibrillation.

Atrial fibrillation increases the risk of stroke and heart failure and can shorten life. Previous studies have also linked these painkillers -- called nonsteroidal anti-inflammatory drugs, or NSAIDs -- to a risk of heart attack and stroke, the researchers noted.

Although this study is only able to show an association between prescription NSAIDs and the risk for atrial fibrillation, lead researcher Dr. Bruno Stricker, a professor of pharmacoepidemiology at Erasmus Medical Center in Rotterdam, the Netherlands, said he believes that this link "suggests a cause-effect relationship."

However, one U.S. expert believes more research is needed.

"Further studies are needed to evaluate use of NSAIDs and risk of atrial fibrillation," said Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, and a spokesman for the American Heart Association.

For the study, Stricker's team collected data on over 8,400 people who took part in the Rotterdam Study. Since 1990, that study has been tracking the health of people 55 and older who live in one area of the Dutch city.

During the average follow-up period of just under 13 years, 857 of the participants developed atrial fibrillation. Of these, 261 had never used prescription-strength NSAIDs, 554 had used them in the past and 42 were currently taking them.

People who were current, chronic users of NSAIDs had a 76 percent higher risk of atrial fibrillation than those who had never used them. The risk remained even after taking into account other risk factors, such as age, sex and heart problems, Stricker's group found.

For people who used NSAIDs within the previous month, the risk for atrial fibrillation rose to 84 percent, the study authors added.

Although the risk seemed higher with larger doses of these prescription painkillers, the trend wasn't significant, the researchers noted. The study did not examine use of over-the-counter versions of NSAIDs, which include drugs such as Aleve, Advil and Motrin.

Fonarow said NSAID medications have come under scrutiny in the past.

"Use of NSAIDs has been shown to be associated with heart disease, kidney disease and increased risk of heart failure and heart failure hospitalizations," Fonarow noted. Some recent studies have also suggested that NSAID use is associated with an increased risk of atrial fibrillation, and this new study provides further evidence of an association, Fonarow said.

However, he added that for people not already at high risk for the irregular heartbeat, using an NSAID "in moderation" seems reasonable as long as there is no other medical reason to avoid the drug.

How prescription NSAIDs might increase the risk for atrial fibrillation isn't clear, but study author Stricker speculated that it might be connected to fluid retention caused by these drugs making blood pressure go up.

The need to take a prescription-strength NSAID might also indicate underlying inflammation, which boosts the risk of atrial fibrillation, the researchers suggested. In other words, it might be the underlying medical condition that is the problem, not the drug.